This invention generally relates to combustor liners, such as those used on Honeywell TPE331-10, TPE331-11, and TPE331-12 series turbine aircraft engines and, more particularly, to methods for controlling carbon formation within such repaired combustor liners and constructing such combustor liners.
A turbine engine typically includes a compressor section, combustion section, and a turbine section. Within the combustion section is the combustor liner wherein fuel is burned producing a hot gas usually at an intensely high temperature. To prevent this high temperature heat from damaging the combustor liner before it exits to the turbine section, the interior of the combustor liner is provided with effusion holes and film cooling, and may include thermal barrier coating. This combustor liner can be created by securing a series of panels together in series with one panel being secured to a dome assembly. The effusion holes and film cooling, and thermal barrier coating, of the combustor liner prevents the intense combustion heat from damaging the combustor liner as well as the rest of the engine. The combustor liner, however, becomes very hot in the process.
A negative effect of the intense heat in the combustion process is the build-up of carbon on the combustion liner near the dome assembly. Over time, the carbon build-up can break off the combustion liner and pass through the turbine section. When this occurs, the carbon build-up may strike the turbine blades located therein, causing damage to those blades. This reduces the life span of the turbine blades and requires more frequent repairs to the engine.
U.S. Pat. Nos. 6,581,285 and 6,568,079 describe a method of replacing combustor liner panels. The inner and outer liners include a series of panels and between which are nuggets. The inner and outer liners are attached to a dome assembly by respective bolt bands that enable fasteners to be removed and re-attached to the liners and dome assembly. In the event of a damaged panel, a cut is made through at least one panel or nugget to remove the damaged panel and replace it with new panel. However, some of the disadvantages of this method include distortion and blockage of the cooling air metering holes if the cut and subsequent weld is in the nugget adjacent to such holes. Loss of thermal barrier coating can result if the cut and subsequent weld is in the area of the thermal barrier coated panel. The use of fasteners for assembling combustor liners can affect the combustion process and engine performance, due to leakage of air around such fasteners, and the loss of heat transfer through this joining method.
A combustor liner developed by the applicants herein is shown in partial cross-section in FIG. 1. In this combustor liner 100, a generally cylindrical outer liner subassembly 102 encloses a generally cylindrical inner liner subassembly 103, both of which are integrated (i.e., non-modular) with a dome subassembly 110. The inner liner subassembly 103 includes a plurality of inner panels 103a of decreasing diameter 113 with one of the panels 103a integrated with the dome subassembly 110. The inner panel integrated with the dome assembly 110 includes four rows of 181 effusion holes 104, while the panel that is second closest to the dome assembly includes five rows of 206 effusion holes 104.
Likewise, and as better shown in FIG. 2, the outer liner subassembly 102 is made up of plurality of outer panels 102a, of which one is integrated (i.e., non-modular) with the dome assembly 110. Each panel 102a has a decreasing diameter 112, (FIG. 1) to accommodate the attachment of the panels to one another. Eleven rows 106 of effusions holes 108 are in the outer panel 102a closest to the dome assembly 110. A first group 105a of seven rows 106, which are the closest rows to the dome assembly 110, has 239 effusion holes in each row. A second group 105b of four rows 106, which are the farthest rows to the dome assembly, has 281 effusion holes in each row. The effusion hole configuration, however, can stress the panel closest to the dome assembly 110, resulting in a shorter lifespan of the outer liner subassembly 102 and consequently the entire combustor liner 100 since the inner and outer liner subassemblies are integrated with the dome assembly.
As can be seen, there is a need to improve the ease of replacement of either the inner and/or outer liner subassemblies to eliminate the need to replace the entire combustor liner.